DE1184335B - Process for the production of acetylene from gas mixtures - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school Class: C 07 c

German class: 12 ο - 19/01

Number: 1 184 335

File number: B 71781IV b / 12 ο

Registration date: May 7, 1963

Opening day: December 31, 1964

For the separation of acetylene from gas mixtures, especially from those that are generated by thermal or electrical fission of hydrocarbons obtained with or without oxygen are processes known in which the acetylene is washed out of the gas mixture by a solvent will. This washout is carried out under increased pressure in order to be as large as possible Amount of acetylene to dissolve. The dissolved acetylene is extracted from the washing liquid by reducing the pressure or temperature increase or both measures together set free. It can then in countercurrent with the washing liquid of compounds that are less soluble than acetylene to be freed. ,

When washing out the acetylene, compounds are separated from the gas mixture in addition to acetylene, which are more soluble than acetylene (e.g. methylacetylene, vinyl acetylene and diacetylene). These can after outgassing the acetylene at an elevated temperature and preferably at a reduced temperature Pressure expelled with the help of steam from the washing liquid and as a mixture with Steam can be drawn off. The degassed washing liquid is then used again for washing out used by acetylene (Chemie-Ingenieur-Technik, 26, p. 253 [1954]).

It is also known that the gas obtained by splitting hydrocarbons before compression and washing off the acetylene with a small amount of the same solvent that is used for the leaching of acetylene is used to wash (prewash) and thereby compounds from the gas that cause pollution and clogging in the compressor. That are in particular polycyclic hydrocarbons, e.g. B. naphthalene, methylnaphthalenes, acenaphthalene and acenaphthene. The small amount of washing liquid loaded with these compounds from the pre-wash is used together with the larger one used to wash out the acetylene under pressure Amount of washing liquid (main wash) freed from the absorbed substances. The union of With this method, the two washing liquids are expediently carried out after the larger one Amount of washing liquid released acetylene in countercurrent with the washing liquid Main wash has been cleaned (German Auslegeschrift 1 040 171).

It is also known to first process acetylene from the acetylene-containing gas mixture at normal pressure or at elevated pressure with a small amount of solvent
Gas mixtures

Applicant:

Aniline & Soda Factory in Baden

Corporation,

Ludwigshafen / Rhine

Named as inventor:
Dr. Hans Fritz, Ludwigshafen / Rhine;
Dr. Martin Reichert, Frankenthal (Palatinate);
Dr. Ulrich Wagner, Ludwigshafen / Rhine

to wash out all of the diacetylene, the scrubbing liquid laden with diacetylene by stripping to free from diacetylene with gas or steam, from the diacetylene-free gas mixture with a larger Amount of the same solvent of acetylene to wash out under the same pressure and the dissolved Expelling acetylene from the washing liquid again by heating (USA.Patent 2,726,734 and German patents 763 084, 578 072, 669 307).

Suitable solvents for these processes are e.g. butyrolactone and N-methylpyrrolidone (German Patent specification 874 773).

When acetylene is separated from gas mixtures by the known processes, polymerization products are formed in the scrubbing liquid which cannot be removed from the scrubbing liquid by degassing. Some of these polymers remain dissolved in the washing liquid and must be removed from it by complete or partial distillation of the washing liquid. Another part is deposited in solid form, e.g. B1 in heat exchangers and columns, as a result of which the heat transfer is worsened and the passage of gas and liquid is made difficult;

It has now been found that the amount of polymers formed is considerably reduced, if the washing liquid obtained during the pre-wash with the withdrawn mixture of water

409 760/399

and / or solvent vapor and compounds soluble better than acetylene, preferably im Countercurrent, brings in contact. The washing liquid treated in this way from the pre-wash is expedient alone or with the washing liquid freed from acetylene and more soluble compounds combined from the main wash used again as washing liquid.

It is advantageous to remove the non-volatile constituents from the washing liquid or a part thereof by distillation and used the purified washing liquid together with the degassed Wash liquid from the main wash and optionally the rest of the wash liquid from the pre-wash again for the two washes.

It may be expedient to remove from the solvent to be returned to the prewash all or part of the water contained.

It is sufficient to measure the amount of solvent for the prewash so that only part of the diacetylene is absorbed in the prewash. The same effect is also achieved if all of the diacetylene is washed out of the cracked gas in the pre-wash. Any possibly absorbed during the pre-wash small amount of acetylene can in a known manner by stripping the solvent from the Prewash with an inert gas, e.g. B. part of the practically acetylene-free obtained in the main wash Lean gases, removed from the solvent and fed back upstream of the compressor.

The following examples and drawings explain the implementation of the method according to Invention.

example 1

Partial oxidation of hydrocarbons produces a gas mixture of the following average composition manufactured (volume percentage):

Acetylene 8.4

CgH ^ hydrocarbons .. 0.13

Vinyl acetylene ............ 0.04

Diacetylene. 0.23

Ethylene ..., ... 0.2

Carbon dioxide 3.8

Carbon dioxide 37.8

Hydrogen: .... 43.5

Nitrogen 1.9

Oxygen. ··. ·· 0.1 _;

In addition, naphthalene, acenaphthene and acenaphthylene are in low concentrations in the gas mixture has been proven. .

Every hour, 640Nm ^{8 of} this gas are added in a device according to FIG. a pressure of 1.03 atm abs. and passed at a temperature of 25 ° C through line 1 into the pre-washer 2. 125 kg of N-methylpyrrolidone are fed in via line 3. A gas with 0.15 percent by volume of diacetylene is drawn off through line 4. So 34.8% of the diacetylene is washed out. The washed gas is in the compressor 5 to 10 atm abs. compressed and washed in the washing tower 6 with 3,900 kg of N-methylpyrrolidone, which flow in through line 7 at 28 ° C. ^{583 Nm 3 of} a gas with the following average composition are withdrawn through line 8 (percent by volume):

Acetylene - 0.1

Ethylene 0.2 ■ -.- ■ -

Methane 4.3

■■ ^; Carbon dioxide 4.2

Carbon dioxide 41.4

Hydrogen 47.6

Oxygen 0.1

Nitrogen 2.1

The detergent loaded with acetylene and some of the other components contained in the raw gas leaves the tower 6 through the line 9, arrives relaxation to 1.2 atm abs. ia den Rectification tower 10 and from there through line 11

ao in the degassing tower 12, where by heating to 100 ° C and reducing the pressure to 0.2 atm abs. the dissolved gases are set free. They get through the line 13 to the ater part of the rectifying tower 10, in which they flow counter to the detergent flowing down. A part of the acetylene leaves the tower 10 through the line 14 with the gases displaced from the solution and is fed to the suction line of the compressor 5. Through line 15 are 53 Nm ³ acetylene with less than

0.1 ° / α carbon dioxide deducted. · ■

The gas constituents (in addition to small amounts of acetylenes), which are more soluble than acetylene, escape from the degassing tower 12 through the line 16 Methylacetylene, vinylacetylene and diacetyien detected in this gas) and occur as a mixture Water and N-methylpyrrolidone vapor down into the Column 17 a. At the head of column 17 wad the loaded washing liquid passed through the line 29 from the prewash. From the one at the head of the Column 17 withdrawn through line 18 mixture of steam and gas is in column 19 washed out the N-methylpyrrolidone vapor with 100 kg of water, which is fed in through line 20 and the mixture of water vapor and gas is withdrawn through line 21. The through .the Line 22 outflowing mixture of N-Methyipyrfo-Hdon and water is directed to the top of the EntgaBufigsturm 12, in its sump by heating the emerging through the Leitbung 16 generated steam

will. .. ·. ■■ ·: ■ ■ ·

The scrubbing liquid degassed in the column 12 is largely passed through the lines 23 and 7 to the head of the scrubbing tower 6, the remainder flowing through the line 3 to the head of the absorber 2; In the Sufiipf of Column 17; the water contained in the washing liquid flowing down is driven out by means of heating, the washing liquid leaves the column through line 24, from which a partial stream of 60 kg is withdrawn for distillation 25, the remainder flows through line 26 to the head of the prewasher 2: The After condensation and cooling, distillate from 25 flows through lines 27 and 7 to the head of the washing tower 6. At 28, 0.12 kg of highly volatile constituents become; deducted ·. ■ ■ .-.

The washing liquid is contained in the sump of the Eütgasungsturm 12 0.06 percent by weight; dissolved polymers, 17.0.2 percent by weight of dissolved polymers in the bottom of the column.

5 6

The function of the remaining device parts is described below for comparison and the results achieved in this case correspond to those in Example 1 and FIG. 1. wrote. When comparing the

By partial oxidation of hydrocarbons, non-volatile contamination was found at point 28 a gas mixture of the following average composition: 0 ^ 12 kg, and that in the sump of demensification produced (volume percent): gassing tower 12 contained polymers, 0.06 Ge

weight percent with the corresponding values that

Acetylene 9.0 when working according to a known method

C ₃ H ₄ hydrocarbons .. 0.12 will hold: 0.52 kg and 0.87 percent by weight,

Vinylacetylene 0.05 ¹⁰ ^ clearly that with the method according to the

Diacetvlen q 23 invention related technical progress

Ethylene .. "" !!!!! ""! I ₀ ; ₂ ^know -

Methane 3.9 Example 2

Carbon dioxide 3.6 15 hourly 640 Nm ^{3 of the} same acetylenic

Carbon oxide 37.9 term cracked gas, as described in Example 1, under

Wa ^ rstnff Ai \ ^{otherwise the} same conditions in one device

VYdsserbiuu -w, j according to FIG. 3 in column 2 with 200 kg

Sauerstott ü, l N-methylpyrrolidone washed.

Nitrogen 1.4 ₂₀ The gas withdrawn through line 4 contained

0.0069 volume percent diacetylene, -97% of the diace-

Naphthalene tylens were also washed out in the gas mixture.

Acenaphthylene and acenaphthene in low concentrations from the pre-wash 2 through line 29

centering has been proven. draining laden washing liquid is in the

Every hour 640 Nm ^{3 of} this gas are in a 25 column 30 with the help of 8 Nm ³ of the acce-

Device according to FIG. 2 (known tylene absorption from column 6 escaping

Process) at a pressure of 1.03 atm abs. and gas introduced through line 31 from

at a temperature of 25 ° C. freed acetylene dissolved through line 1 at the top of the column

into the pre-washer2. Acetylene-containing gas exiting via line 3 30 is passed through the

165 kg of N-methylpyrrolidone are added. 30 line 32 to the suction side of the compressor

the line 4 is a gas with 0.13 percent by volume recycled. The draining from the column 30

Diacetylene withdrawn, so there were 43.5% of the solvent is through line 33 to the

Washed out diacetylenes in column 2. This head of the column 17 passed. At 28 will be

Gas is in the compressor 5 to 9 atm abs. Compressed 0.162 kg of dissolved polymers deducted,

miert and in the washing tower 6 with 4330 kg of N-methyl 35 The washing liquid contained in the bottom of the Ent-

pyrrolidone, which at 27 ° C through the line 7 gas supply tower 12 0.073 percent by weight non-volatile

flow, washed. Through the line 8 term polymers, in the bottom of the column 17 0.27 Ge

580 Nm ^{3 of} a gas with the following mean weight percent non-volatile polymers. The remaining

Composition subtracted (volume percentage): quantities, pressures and temperatures as well as the func-

40 tion of the devices according to FIG. 3

Acetylene 0.1 Cl _16n ^ en in Example 1 and Fi g. 1 mentioned

Ethylene 0.2 Figures and indications. You can also tell by this

Methane 4.3 example the low content of polymers in the

Carbon dioxide 3 9 washing liquid when working according to the invention

Carbon oxide .. !!! "!""" 41 ^ 8 ^{45 dung} \

Hydrogen 48.1 Example 3

Oxygen 0.1 per hour are 640 Nm ^{3 of} the same gap nitrogen 1.5 gases as described in Example 1, but in which

so no polycyclic aromatics were contained in

The loaded washing liquid from the pre-wash of a device according to FIG. 4 left in the com the column 2 through line 29 and pressor 5 to 10 atm abs. compressed and through the with the Lö- line 34 running out of the rectification tower 10 into the washing column 35. On the solution in line 11 mixed. Those in the Ent-Head of 35 become 116 kg through line 36 tension tower 12 degassed washing liquid becomes 55 N-methylpyrrolidone at a temperature of 30 ° C largely given by lines 23 and 7 or 3. In the pre-washed gas that passes through the fed back to the two washing stages, while line 37 flows into the washing tower 6, was none a partial stream of 60 kg for the distillation 25 removed diacetylene detected, is pulled. The distillate from 25 is after condensation. The loaded washing liquid from the pre-wash

sation and cooling discharged through line 27. Thus, 1.2 atm abs. passes through line 38 with relaxation on and with the washing 1.2 atm abs. flowing in line 23. in the column 30, combined in the liquid from below. At 28, 0.52 kg are not ^{withdrawn through the line 31 4.3 Nm 3} of the volatile polymer from the wash, the gas withdrawing the washing liquid tower 6 is introduced, in the bottom of the degassing tower 12 contains 0.87 Ge die from the column 30 draining washing liquid

weight percent dissolved polymers. At 20, 65 speed is passed through line 33 to the head of the Ko-110 kg of water supplied. lonne 17 passed, the outlet of the column 17 arrives

^{57.3 Nm 3 of} acetylene are drawn off through line 40 into the degassing tower 12 through line 15 with less than 0.1% carbon dioxide. the bottom of the column 12 is the degassed scrubbing

Most of the liquid is returned to the two washing stages through lines 23 and 7 or 36, a partial stream of 60 kg is withdrawn for distillation 25. The distillate is after condensation and cooling withdrawn through line 27 and with the washing liquid flowing in line 23 united.

At 20, 47 kg of water are added to the top of the column 19.

The washing liquid contained 0.12 percent by weight of dissolved polymers in the bottom of the column 12 28, 0.126 kg of non-volatile polymers was withdrawn.

The other quantities, pressures and temperatures as well as the function of the apparatus correspond to the in example 1 and FIG. 1 mentioned figures and information.

For comparison, the known procedure and the results achieved are described below.

^{640 Nm 3 of the} same cracked gas, as described in the comparative example for example 1, are released per hour at a pressure of 1.03 atm abs. and at a temperature of 25 ° C. in a device according to FIG. 5 passed through line 1 into column 2 and washed with 165 kg of N-methylpyrrolidone flowing in through line 3. The loaded washing liquid flows through line 39 with relaxation to 0.2 atm abs. into the degassing column 40, where it is heated to 100.degree. At the top of the column 40, the expelled gas is drawn off through line 44 in a mixture with water and N-methylpyrrolidone vapor. In the column 45, the N-methylpyrrolidone vapor is washed out by washing with 5 kg of water which flows through the line 48 to the top of the column 45. At the top of the column 45, a mixture of steam and gas in which, in addition to small amounts of acetylene, the compounds diacetylene, vinyl acetylene, naphthalene, acenaphthene and acenaphthylene were detected, is drawn off.

A mixture of water and N-methylpyrrolidone flows through line 47 to the top of degassing column 40, in the bottom of which the steam M emerging through line 44 is generated by heating. The degassed scrubbing liquid is drawn off through line 41 from the bottom of column 40. Of this, 105 kg are passed through the line to the top of the prewash column 2, kg flow through the line 42 to the distillation 25.

After condensation and cooling, the distillate from 25 is turned upside down through lines 27 and 7 the scrubbing column 6 passed, of the scrubbing liquid draining from the gassing tower 12, the is returned to the scrubbing column 6 through lines 23 and 7, are through lines 49 and 3 60 kg passed into the prewash column 2.

At 28, 0.475 kg of non-volatile components are drawn off, the washing liquid contains in the sump the column 41 0.79 percent by weight of dissolved polymers, in the bottom of the column 12 0.07 percent by weight of dissolved polymers.

The other quantities, pressures and temperatures as well as the function of the other apparatus correspond the numbers and information given in the comparative example for example 1. Here too, the Compared to Example 3, the low polymer content of the washing liquid when working according to the method of the invention.

Claims (1)

Claim: Process for the production of acetylene from gas mixtures, such as those used in thermal or electrical splitting of hydrocarbons with or without oxygen, by pre-washing the gas mixture with a solvent for acetylene, washing out the acetylene in the main wash with a larger amount of the same solvent under pressure, expulsion of the acetylene from the washing liquid thus obtained, cleaning of the expelled acetylene in countercurrent with the washing liquid, removal of compounds that are more soluble than acetylene from the washing liquid by water and / or solvent vapor, optionally with reduced pressure, and removal of the gaseous compounds which are more soluble than acetylene together with the water and / or solvent vapor, characterized in that that the washing liquid obtained in the prewash with the withdrawn mixture Bringing water and / or solvent vapor and more soluble than acetylene compounds, preferably in countercurrent, into contact. For this purpose 2 sheets of drawings 409 760/399 12.64 © Bundesdruckerei Berlin